How long for mortar to set before adding windows

[Red_Shift]

Quick question guys. I'm adding a porch which means my two large front Windows have to be replaced with smaller ones. I've removed the old Windows and built block work in to the new window size. How long before I can drill into the new block work to fix the Windows? (I will be using metal fixing strip to bridge the cavity). I was going to leave it a week. Thanks.

 

[tomfe]

If you are very careful 48 hours, but if you can leave it a week all the better.

 

[^woody^]

Foam fix next day

 

[pilsbury]

Foam fix next day

Special foam or just regular expanding foam in a can? Will that hold as well as concrete screws?

 

[^woody^]

Any foam. It will hold, but screws are recommended too.

 

[Red_Shift]

Thanks guys, I'm going to follow my spidy sense and put them in on Thursday, 84 hours after block work done. 24 hours later they are solid. I tend to majorly over engineer when it's my own house (ties every course etc).